The homeopathic remedy, Allium cepa, made of potentized red onion, can help the body overcome a cold or allergy attack in which the person has similar symptoms (watery eyes, runny nose, sneezing, coughing.) Even though the symptoms were not caused by exposure to an onion, the remedy made from the onion can help the body overcome them, because the symptoms are similar. A com example used to describe this effect is that of the person chopping an onion When a healthy person chops an onion they usually get watery eyes, and a a runny nose. They may even experience sneezing or coughing, from exposure to the active substances in the onion. It is based on the Law of Similars and potentization. Basically, the Law of Similars is the premise that because exposure to a given substance can cause specific symptoms in someone who is healthy, then that substance - given as a homeopathic remedy - will stimulate the body's own curative powers to overcome similar symptoms during illness.

Homeopathy is a non-toxic system of medicine used to treat a wide variety of health concerns.